RSHD(8) BSD System Manager's Manual RSHD(8)NAME
rshd -- remote shell server
SYNOPSIS
rshd [-aiklnvxPL] [-p port]
DESCRIPTION
rshd is the server for the rsh(1) program. It provides an authenticated remote command execution service. Supported options are:
-n, --no-keepalive
Disables keep-alive messages. Keep-alives are packets sent at certain intervals to make sure that the client is still there, even
when it doesn't send any data.
-k, --kerberos
Assume that clients connecting to this server will use some form of Kerberos authentication. See the EXAMPLES section for a sample
inetd.conf(5) configuration.
-x, --encrypt
For Kerberos 4 this means that the connections are encrypted. Kerberos 5 can negotiate encryption even without this option, but if
it's present rshd will deny unencrypted connections. This option implies -k.
-v, --vacuous
If the connecting client does not use any Kerberised authentication, print a message that complains about this fact, and exit. This
is helpful if you want to move away from old port-based authentication.
-P When using the AFS filesystem, users' authentication tokens are put in something called a PAG (Process Authentication Group). Multi-
ple processes can share a PAG, but normally each login session has its own PAG. This option disables the setpag() call, so all tokens
will be put in the default (uid-based) PAG, making it possible to share tokens between sessions. This is only useful in peculiar
environments, such as some batch systems.
-i, --no-inetd
The -i option will cause rshd to create a socket, instead of assuming that its stdin came from inetd(8). This is mostly useful for
debugging.
-p port, --port=port
Port to use with -i.
-a This flag is for backwards compatibility only.
-L This flag enables logging of connections to syslogd(8). This option is always on in this implementation.
FILES
/etc/hosts.equiv
~/.rhosts
EXAMPLES
The following can be used to enable Kerberised rsh in inetd.cond(5), while disabling non-Kerberised connections:
shell stream tcp nowait root /usr/libexec/rshd rshd -v
kshell stream tcp nowait root /usr/libexec/rshd rshd -k
ekshell stream tcp nowait root /usr/libexec/rshd rshd -kx
SEE ALSO rsh(1), iruserok(3)HISTORY
The rshd command appeared in 4.2BSD.
AUTHORS
This implementation of rshd was written as part of the Heimdal Kerberos 5 implementation.
HEIMDAL November 22, 2002 HEIMDAL
Check Out this Related Man Page
RSH(1) BSD General Commands Manual RSH(1)NAME
rsh -- remote shell
SYNOPSIS
rsh [-45FGKdefnuxz] [-U string] [-p port] [-l username] [-P N|O] host [command]
DESCRIPTION
rsh authenticates to the rshd(8) daemon on the remote host, and then executes the specified command.
rsh copies its standard input to the remote command, and the standard output and error of the remote command to its own.
Valid options are:
-4, --krb4
The -4 option requests Kerberos 4 authentication. Normally all supported authentication mechanisms will be tried, but in some cases
more explicit control is desired.
-5, --krb5
The -5 option requests Kerberos 5 authentication. This is analogous to the -4 option.
-K, --broken
The -K option turns off all Kerberos authentication. The security in this mode relies on reserved ports. The long name is an indica-
tion of how good this is.
-n, --no-input
The -n option directs the input from the /dev/null device (see the BUGS section of this manual page).
-d Enable setsockopt(2) socket debugging.
-e, --no-stderr
Don't use a separate socket for the stderr stream. This can be necessary if rsh-ing through a NAT bridge.
-x, --encrypt
The -x option enables encryption for all data exchange. This is only valid for Kerberos authenticated connections (see the BUGS sec-
tion for limitations).
-z The opposite of -x. This is the default, and is mainly useful if encryption has been enabled by default, for instance in the
appdefaults section of /etc/krb5.conf when using Kerberos 5.
-f, --forward
Forward Kerberos 5 credentials to the remote host. Also settable via appdefaults (see krb5.conf).
-F, --forwardable
Make the forwarded credentials re-forwardable. Also settable via appdefaults (see krb5.conf).
-l string, --user=string
By default the remote username is the same as the local. The -l option or the username@host format allow the remote name to be speci-
fied.
-n, --no-input
Direct input from /dev/null (see the BUGS section).
-p number-or-service, --port=number-or-service
Connect to this port instead of the default (which is 514 when using old port based authentication, 544 for Kerberos 5 and non-
encrypted Kerberos 4, and 545 for encrytpted Kerberos 4; subject of course to the contents of /etc/services).
-P N|O|1|2, --protocol=N|O|1|2
Specifies the protocol version to use with Kerberos 5. N and 2 select protocol version 2, while O and 1 select version 1. Version 2
is believed to be more secure, and is the default. Unless asked for a specific version, rsh will try both. This behaviour may change
in the future.
-u, --unique
Make sure the remote credentials cache is unique, that is, don't reuse any existing cache. Mutually exclusive to -U.
-U string, --tkfile=string
Name of the remote credentials cache. Mutually exclusive to -u.
-x, --encrypt
The -x option enables encryption for all data exchange. This is only valid for Kerberos authenticated connections (see the BUGS sec-
tion for limitations).
-z The opposite of -x. This is the default, but encryption can be enabled when using Kerberos 5, by setting the libdefaults/encrypt
option in krb5.conf(5).
EXAMPLES
Care should be taken when issuing commands containing shell meta characters. Without quoting, these will be expanded on the local machine.
The following command:
rsh otherhost cat remotefile > localfile
will write the contents of the remote remotefile to the local localfile, but:
rsh otherhost 'cat remotefile > remotefile2'
will write it to the remote remotefile2.
FILES
/etc/hosts
SEE ALSO ktelnet(1), krb_realmofhost(3), krb_sendauth(3), hosts.equiv(5), krb5.conf(5), rhosts(5), kerberos(8)rshd(8)HISTORY
The rsh command appeared in 4.2BSD.
AUTHORS
This implementation of rsh was written as part of the Heimdal Kerberos 5 implementation.
BUGS
Some shells (notably csh(1)) will cause rsh to block if run in the background, unless the standard input is directed away from the terminal.
This is what the -n option is for.
The -x options enables encryption for the session, but for both Kerberos 4 and 5 the actual command is sent unencrypted, so you should not
send any secret information in the command line (which is probably a bad idea anyway, since the command line can usually be read with tools
like ps(1)). Forthermore in Kerberos 4 the command is not even integrity protected, so anyone with the right tools can modify the command.
HEIMDAL February 20, 2004 HEIMDAL